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951.
菜豆热激蛋白在生物膜上的定位 总被引:8,自引:0,他引:8
选用菜豆 Phaseolus vulgris L. 下胚轴 ,运用35S- Met标记放射自显影和二维电泳技术 ,研究热激蛋白 HSPs 的表达和在生物膜组分中的定位 .实验结果表明 ,盐溶蛋白中主要HSPs为 70 k D HSPs和小分子量 HSPs,而小分子量组 HSPs大量富集在质膜和液泡膜组分中 . 相似文献
952.
干燥番茄(Lycopersicon esculentum Mill. cv. Moneym aker)种子浸种吸水有明显的3 个阶段,尽管种子不同部分吸水的速度不一样,但整粒种子需10~12 h 才能基本完成第一阶段的吸水。胚乳对种胚伸长和生长的机械压力明显阻碍种胚的吸水,即使在第二阶段整个种子水势与浸种溶液基本达到水分平衡时,种胚的水势仍然低于整个种子水势0.6~0.9 MPa。发芽过程中GA 和ABA不直接影响番茄种子吸水。番茄种胚水势与含水量的关系呈幂指数的正相关。无论在浸种还是渗控处理过程中,番茄种胚压力势的总变化趋势是下降的 相似文献
953.
牛生长激素基因在马铃薯中的表达 总被引:5,自引:0,他引:5
将牛生长激素基因cDNA 与Patatin ClassI启动子及NOS3终止子连接,构建了表达载体pPBGT. 用直接法将表达载体转入农杆菌(Agrobacterium tum efaciens) LBA4404(pRAL4404)菌株, 用此菌株转化马铃薯(Solanum tuberosum )得到再生植株. 经NPTⅡ活性检测,总DNA PCR和Southern blot证明目的基因已整合到马铃薯基因组中.RNA 点杂交和Western blot表明牛生长激素基因已在转基因马铃薯块茎中转录和表达 相似文献
954.
955.
NMR characterisation of a triple stranded complex formed by homo-purine and homo-pyrimidine DNA strands at 1:1 molar ratio and acidic pH. 总被引:1,自引:1,他引:0
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Homo-purine (d-TGAGGAAAGAAGGT) and homo-pyrimidine (d-CTCCTTTCTTCC) oligomers have been designed such that they are complementary in parallel orientation. When mixed in a 1:1 molar ratio, the system adopts an antiparallel duplex at neutral pH with three mismatched base pairs. On lowering the pH below 5.5, a new complex is formed. The NMR results show the coexistence of a intermolecular pyrimidine.purine:pyrimidine DNA triplex and a single stranded oligopurine at this pH. The triplex is stabilized by five T.A:T, four C+.G:C and two mismatched triads, namely, C+.G-T and T.A-C. This triplex is further stabilized by a Hoogsteen C+.G base-pair on one end. Temperature dependence of the imino proton resonances reveals that the triplex dissociates directly into single strands around 55 degrees C, without duplex intermediates. Parallel duplexes are not formed under any of the conditions employed in this study. 相似文献
956.
The group I self-splicing introns found in many organisms are competitively inhibited by L-arginine. We have found that L-arginine acts stereoselectively on the Pc1. LSU nuclear group I intron of Pneumocystis carinii, competitively inhibiting the first (cleavage) step of the splicing reaction and stimulating the second (ligation) step. Stimulation of the second step is most clearly demonstrated in reactions whose first step is blocked after 15 min by addition of pentamidine. The guanidine moiety of arginine is required for both effects. L-Canavanine is a more potent inhibitor than L-arginine yet it fails to stimulate. L-Arginine derivatized on its carboxyl group as an amide, ester or peptide is more potent than L-arginine as a stimulator and inhibitor, with di-arginine amide and tri-arginine being the most potent effectors tested. The most potent peptides tested are 10,000 times as effective as L-arginine in inhibiting ribozyme activity, and nearly 400 times as effective as stimulators. Arginine and some of its derivatives apparently bind to site(s) on the ribozyme to alter its conformation to one more active in the second step of splicing while competing with guanosine substrate in the first step. This phenomenon indicates that ribozymes, like protein enzymes, can be inhibited or stimulated by non-substrate low molecular weight compounds, which suggests that such compounds may be developed as pharmacological agents acting on RNA targets. 相似文献
957.
Catherine M. Phelan Lu Liu Martin H. Ruttledge Kristina Müntzning Per-Åke Ridderheim Vincent P. Collins 《Human genetics》1995,96(6):684-690
Central nervous system (CNS) tumours are the most common solid tumours in children. Cytogenetic and molecular genetic studies of these neoplasms have previously shown abnormalities of chromosome 17, implicating genes on this autosome in tumorigenesis. To identify mutations in the TP53 tumour suppressor gene (17p13.1), we have sequenced the five highly conserved regions of this gene in 29 mixed paediatric CNS tumors. No mutations were detected by this analysis. In order to identify other candidate disease loci on chromosome 17, we have carried out a detailed deletion mapping analysis using 16 polymorphic DNA markers on 19 of the above tumours and an additional four cases. Abnormalities of chromosome 17 occurred in nine cases (39%), six of which were primitive neuroectodermal tumour (PNET)-medulloblastomas. These findings suggest that it is unlikely that the TP53 gene is directly involved in the development of common paediatric brain tumours. This is in contrast to findings from adult brain and other tumour types. Moreover, the frequency of chromosome 17 aberrations, especially in PNET-medulloblastomas, suggests that other genes on this chromosome contribute to tumourigenesis. 相似文献
958.
He Liu H. Peter Spielmann Nikolai B. Ulyanov David E. Wemmer Thomas L. James 《Journal of biomolecular NMR》1995,6(4):390-402
Summary The effect of experimental and integration errors on the calculations in interproton distances from NOE intensities is examined. It is shown that NOE intensity errors can have a large impact on the distances determined. When multiple spin (spin diffusion) effects are significant, the calculated distances are often underestimated, even when using a complete relaxation matrix analysis. In this case, the bias of distances to smaller values is due to the random errors in the NOE intensities. We show here that accurate upper and lower bounds of the distances can be obtained if the intensity errors are properly accounted for in the complete relaxation matrix calculations, specifically the MARDIGRAS algorithm. The basic MARDIGRAS algorithm has been previously described [Borgias, B.A. and James, T.L. (1990) J. Magn. Reson., 87, 475–487]. It has been shown to provide reasonably good interproton distance bounds, but experimental errors can compromise the quality of the resulting restraints, especially for weak cross peaks. In a new approach introduced here, termed RANDMARDI (random error MARDIGRAS), errors due to random noise and integration errors are mimicked by the addition of random numbers from within a specified range to each input intensity. Interproton distances are then calculated for the modified intensity set using MARDIGRAS. The distribution of distances that define the upper and lower distance bounds is obtained by using N randomly modified intensity sets. RANDMARDI has been used in the solution structure determination of the interstrand cross-link (XL) formed between 4-hydroxymethyl-4,5,8-trimethylpsoralen (HMT) and the DNA oligomer d(5-GCGTACGC-3)2 [Spielmann, H.P. et al. (1995) Biochemistry, 34, 12937–12953]. RANDMARDI generates accurate distance bounds from the experimental NOESY cross-peak intensities for the fixed (known) interproton distances in XL. This provides an independent internal check for the ability of RANDMARDI to accurately fit the experimental data. The XL structure determined using RANDMARDI-generated restrains is in good agreement with other biophysical data that indicate that there is no bend introduced into the DNA by the cross-link. In contrast, isolated spin-pair approximation calculations give distance restraints that, when applied in a restrained molecular dynamics protocol, produce a bent structure.Abbreviations NOE
nuclear Overhauser effect
- SD
standard deviation
- HMT
4-hydroxymethyl-4,5,8-trimethylpsoralen
- XL
psoralen-DNA interstrand cross-link 相似文献
959.
A. L. Archibald C. S. Haley J. F. Brown S. Couperwhite H. A. McQueen D. Nicholson W. Coppieters A. Van de Weghe A. Stratil A. K. Winterø M. Fredholm N. J. Larsen V. H. Nielsen D. Milan N. Woloszyn A. Robic M. Dalens J. Riquet J. Gellin J. -C. Caritez G. Burgaud L. Ollivier J. -P. Bidanel M. Vaiman C. Renard H. Geldermann R. Davoli D. Ruyter E. J. M. Verstege M. A. M. Groenen W. Davies B. Høyheim A. Keiserud L. Andersson H. Ellegren M. Johansson L. Marklund J. R. Miller D. V. Anderson Dear E. Signer A. J. Jeffreys C. Moran P. Le Tissier Muladno M. F. Rothschild C. K. Tuggle D. Vaske J. Helm H. -C. Liu A. Rahman T. -P. Yu R. G. Larson C. B. Schmitz 《Mammalian genome》1995,6(3):157-175
A linkage map of the porcine genome has been developed by segregation analysis of 239 genetic markers. Eighty-one of these markers correspond to known genes. Linkage groups have been assigned to all 18 autosomes plus the X Chromosome (Chr). As 69 of the markers on the linkage map have also been mapped physically (by others), there is significant integration of linkage and physical map data. Six informative markers failed to show linkage to these maps. As in other species, the genetic map of the heterogametic sex (male) was significantly shorter (16.5 Morgans) than the genetic map of the homogametic sex (female) (21.5 Morgans). The sex-averaged genetic map of the pig was estimated to be 18 Morgans in length. Mapping information for 61 Type I loci (genes) enhances the contribution of the pig gene map to comparative gene mapping. Because the linkage map incorporates both highly polymorphic Type II loci, predominantly microsatellites, and Type I loci, it will be useful both for large experiments to map quantitative trait loci and for the subsequent isolation of trait genes following a comparative and candidate gene approach. 相似文献
960.
Adding olive oil to an insect cell (Spodoptera frugiperda) cultivation with a TNM-FH medium enhanced cell growth. In the static cultivation, growth with 0.5% oil increased viable cell density by 32%, while cultivation in spinner flasks agitated at 260 rpm increased by 64%. With a gradual increase of agitation from 60 rpm to 500 rpm, the viable cell density was 81% higher than that without the olive oil supplement. 相似文献